U.S. Sen. Mitch McConnell and potential Democratic challenger Alison Lundergan Grimes are tied in a new poll of Kentucky voters, though state Republicans are calling the results a "sham."

The poll, by Public Policy Polling, stated that McConnell and Grimes were each supported by 45 percent of Kentucky voters. In April, a PPP poll showed Grimes trailing by 4 points. In December, she trailed by 7 points.

The PPP poll was paid for by the Senate Majority PAC, an organization founded with the help of Democratic U.S. Senator Harry Reid, the current majority leader.

Republicans are characterizing the results as "push polling"—a poll that tries to influence answers through the questions asked.

The PPP poll's critics say the questions directly comment about McConnell, his tenure in the Senate or some of his votes, rather than asking more simple questions as scientific polls often do.

"The Obama-Democrats' playbook for recruiting a candidate to be their sacrificial lamb is centered on sham polling and big promises. PPP, this time polling directly for their client Harry Reid, has been a centerpiece of this effort with laughable poll questions, statistical abnormalities, and conclusions so ridiculous even the most partisan observer can't possibly take them seriously," Benton says.

Kelsey Cooper, a spokeswoman for the Republican Party of Kentucky, says the polling firm is being used as a front for Democratic recruiting efforts.

"PPP polls have always been ridiculous, but this survey takes it to a whole new level. The liberal partisan outfit, working for their client Harry Reid, employs laughable poll questions, statistical abnormalities, and breathtakingly bad conclusions in an attempt to recruit a candidate to carry Obama's flag in Kentucky. In reality, Kentucky Democrats are on the run and unable to find a top-tier candidate because they know Sen. McConnell is working hard for Kentucky and is well positioned for re-election," Cooper says.

PPP is often considered a Democratic-leaning polling firm, because it does most of its non-public work for such groups. But it was also found to be the most accurate pollster in the 2012 election cycle, according to the Hill.

The Kentucky Secretary of State has yet to make a decision on whether to enter the Senate race, but she has acknowledged she has been encouraged to run and is considering such a campaign.

The poll also showed McConnell "underwater" in approval ratings, with 47 percent disapproving of him, with 44 percent approving.

Incumbents typically like to have both their head-to-head matchup and approval ratings about 50 percent to be considered safe. Kentucky Democrats say the poll shows what they already know about the race: that McConnell is very vulnerable.

"This poll confirms what we already knew. Senator McConnell has been sacrificing the needs of the Commonwealth for his own political ambition, and Kentucky families are paying attention. He's turned his back on Kentucky's workers, turned his back on women, even turned his back on many of his own positions, and now Kentuckians are turning their backs on him. There's still a year and a half until Election Day, but we're in a great position to retire Mitch McConnell in 2014," Kentucky Democratic Party chairman Dan Logsdon says.

The PPP poll said that McConnell had the support of 74 percent of Republicans and a slight lead over Grimes among independents. Grimes had the support of 65 percent of Democrats. Ten percent of people polled were undecided about the match-up.